A senior republican is suspected of being the leader of an organised dissident crime gang that has built up a big property portfolio from the proceeds of illegal tobacco and alcohol smuggling.

The suspect was sentenced to 15 years imprisonment in the mid-1980s for his role in terrorist offences in Northern Ireland.

He initially supported the Provisional ceasefire but then allegedly defected to a dissident group. He was charged in the Special Criminal Court in Dublin of being a member of the Real IRA but the charge was later withdrawn. He and his alleged associates are now prime targets for the Republic's Criminal Assets Bureau (CAB). As part of their investigation, CAB, backed up by heavily armed officers from the Garda Emergency Response Unit, searched eight premises in counties Monaghan and Cavan yesterday morning.

Three of the six houses raided are said to be owned by the suspect. Also searched were the offices of a solicitor's firm and an auctioneering company.

CAB seized about €10,000 in sterling and euro in cash along with a quantity of Viagra tablets.

A sheaf of documents and electronic devices were seized for analysis while gardai said evidence of illicit tobacco and alcohol smuggling was also taken for forensic examination.

Gardai said CAB's inquiries centred on an organised crime gang operating in the border area and heavily involved in the importation and distribution of illegal cigarettes and counterfeit goods.

Yesterday's searches were part of an information gathering operation and did not include any arrests. A lengthy investigation is now expected into the alleged attempts by the gang to launder the proceeds of the cross-border smuggling in property investments here and in the UK.

Some of the property portfolio here is alleged to be based in counties Monaghan and Leitrim while other investments are under investigation in the UK.

The suspect has been on the radar of police and customs officers on both sides of the border for his alleged major role in the highly profitable smuggling rackets in illicit tobacco and alcohol importation for several years.

A court in Northern Ireland previously made a six-figure confiscation order against him after the seizure of smuggled cigarettes. He has also been convicted of evading customs duty.

He was said in the past to be closely involved in the illegal cigarettes racket with another leading republican, who was alleged to have been a member of the Provisional IRA's army council.